Theoretical Study of CO Adsorption Interactions with Cr-Doped Tungsten Oxide/Graphene Composites for Gas Sensor Application

Mohammad Ammar Syaahiran; Abdul Hanif Mahadi; Chee Ming Lim; Muhammad Raziq Rahimi Kooh; Yuan-Fong Chou Chau; Hai-Pang Chiang; Roshan Thotagamuge

doi:10.1021/acsomega.1c04936

Theoretical Study of CO Adsorption Interactions with Cr-Doped Tungsten Oxide/Graphene Composites for Gas Sensor Application

ACS Omega. 2021 Dec 20;7(1):528-539. doi: 10.1021/acsomega.1c04936. eCollection 2022 Jan 11.

Authors

Mohammad Ammar Syaahiran¹, Abdul Hanif Mahadi¹, Chee Ming Lim¹, Muhammad Raziq Rahimi Kooh¹, Yuan-Fong Chou Chau¹, Hai-Pang Chiang², Roshan Thotagamuge¹

Affiliations

¹ Centre for Advanced Material and Energy Sciences, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Brunei Darussalam.
² Department of Optoelectronics and Materials Technology, National Taiwan Ocean University, Keelung 20224, Taiwan.

Abstract

The present study explores the CO adsorption properties with graphene, tungsten oxide/graphene composite, and Cr-doped tungsten oxide/graphene composite using density functional theory (DFT) calculations. The results of the study reveal the Cr-doped tungsten oxide/graphene composites, g-CrW _n-1O_3n (n = 2 to 4), to have a lowered highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap, high surface reactivity, and a strong cluster-graphene binding energy, hence exhibiting a strong adsorption interaction with CO. The CO adsorption interaction shows physisorption properties by having a greater tendency for Mulliken and natural bond orbital (NBO) charge transfer supported by a strong physisorption interaction toward the g-CrW _n-1O_3n (n = 2 to 4) composite with HOMO-LUMO energy gaps of -0.638, -0.486, and -0.327 eV, respectively. The calculated photoelectron spectroscopy (PES) and infrared spectra combined with the visualized electrostatic potential and contour line confirm the population density of the physisorption interaction. The calculated results show that the g-CrW _n-1O_3n composite achieves a greater sensing ability by possessing the highest sensitivity, adsorption, and desorption characteristics for n = 2 (g-CrWO₆ composite). In conclusion, Cr-doped tungsten oxide/graphene has high sensitivity toward CO gas.